kern_core.c revision 1.28
1 /* $NetBSD: kern_core.c,v 1.28 2019/11/20 19:37:53 pgoyette Exp $ */ 2 3 /* 4 * Copyright (c) 1982, 1986, 1989, 1991, 1993 5 * The Regents of the University of California. All rights reserved. 6 * (c) UNIX System Laboratories, Inc. 7 * All or some portions of this file are derived from material licensed 8 * to the University of California by American Telephone and Telegraph 9 * Co. or Unix System Laboratories, Inc. and are reproduced herein with 10 * the permission of UNIX System Laboratories, Inc. 11 * 12 * Redistribution and use in source and binary forms, with or without 13 * modification, are permitted provided that the following conditions 14 * are met: 15 * 1. Redistributions of source code must retain the above copyright 16 * notice, this list of conditions and the following disclaimer. 17 * 2. Redistributions in binary form must reproduce the above copyright 18 * notice, this list of conditions and the following disclaimer in the 19 * documentation and/or other materials provided with the distribution. 20 * 3. Neither the name of the University nor the names of its contributors 21 * may be used to endorse or promote products derived from this software 22 * without specific prior written permission. 23 * 24 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND 25 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 26 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 27 * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE 28 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 29 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 30 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 31 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 32 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 33 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 34 * SUCH DAMAGE. 35 * 36 * @(#)kern_sig.c 8.14 (Berkeley) 5/14/95 37 */ 38 39 #include <sys/cdefs.h> 40 __KERNEL_RCSID(0, "$NetBSD: kern_core.c,v 1.28 2019/11/20 19:37:53 pgoyette Exp $"); 41 42 #include <sys/param.h> 43 #include <sys/vnode.h> 44 #include <sys/namei.h> 45 #include <sys/acct.h> 46 #include <sys/file.h> 47 #include <sys/stat.h> 48 #include <sys/proc.h> 49 #include <sys/exec.h> 50 #include <sys/filedesc.h> 51 #include <sys/kauth.h> 52 #include <sys/module.h> 53 #include <sys/compat_stub.h> 54 55 MODULE(MODULE_CLASS_MISC, coredump, NULL); 56 57 struct coredump_iostate { 58 struct lwp *io_lwp; 59 struct vnode *io_vp; 60 kauth_cred_t io_cred; 61 off_t io_offset; 62 }; 63 64 static int coredump(struct lwp *, const char *); 65 static int coredump_buildname(struct proc *, char *, const char *, size_t); 66 static int coredump_write(struct coredump_iostate *, enum uio_seg segflg, 67 const void *, size_t); 68 static off_t coredump_offset(struct coredump_iostate *); 69 70 static int 71 coredump_modcmd(modcmd_t cmd, void *arg) 72 { 73 74 switch (cmd) { 75 case MODULE_CMD_INIT: 76 MODULE_HOOK_SET(coredump_hook, "coredump", coredump); 77 MODULE_HOOK_SET(coredump_write_hook, "coredump", 78 coredump_write); 79 MODULE_HOOK_SET(coredump_offset_hook, "coredump", 80 coredump_offset); 81 MODULE_HOOK_SET(coredump_netbsd_hook, "coredump", 82 real_coredump_netbsd); 83 MODULE_HOOK_SET(uvm_coredump_walkmap_hook, "coredump", 84 uvm_coredump_walkmap); 85 MODULE_HOOK_SET(uvm_coredump_count_segs_hook, "coredump", 86 uvm_coredump_count_segs); 87 return 0; 88 case MODULE_CMD_FINI: 89 MODULE_HOOK_UNSET(uvm_coredump_count_segs_hook); 90 MODULE_HOOK_UNSET(uvm_coredump_walkmap_hook); 91 MODULE_HOOK_UNSET(coredump_netbsd_hook); 92 MODULE_HOOK_UNSET(coredump_offset_hook); 93 MODULE_HOOK_UNSET(coredump_write_hook); 94 MODULE_HOOK_UNSET(coredump_hook); 95 return 0; 96 default: 97 return ENOTTY; 98 } 99 } 100 101 /* 102 * Dump core, into a file named "progname.core" or "core" (depending on the 103 * value of shortcorename), unless the process was setuid/setgid. 104 */ 105 static int 106 coredump(struct lwp *l, const char *pattern) 107 { 108 struct vnode *vp; 109 struct proc *p; 110 struct vmspace *vm; 111 kauth_cred_t cred; 112 struct pathbuf *pb; 113 struct nameidata nd; 114 struct vattr vattr; 115 struct coredump_iostate io; 116 struct plimit *lim; 117 int error, error1; 118 char *name, *lastslash; 119 120 name = PNBUF_GET(); 121 122 p = l->l_proc; 123 vm = p->p_vmspace; 124 125 mutex_enter(proc_lock); /* p_session */ 126 mutex_enter(p->p_lock); 127 128 /* 129 * Refuse to core if the data + stack + user size is larger than 130 * the core dump limit. XXX THIS IS WRONG, because of mapped 131 * data. 132 */ 133 if (USPACE + ctob(vm->vm_dsize + vm->vm_ssize) >= 134 p->p_rlimit[RLIMIT_CORE].rlim_cur) { 135 error = EFBIG; /* better error code? */ 136 mutex_exit(p->p_lock); 137 mutex_exit(proc_lock); 138 goto done; 139 } 140 141 /* 142 * It may well not be curproc, so grab a reference to its current 143 * credentials. 144 */ 145 kauth_cred_hold(p->p_cred); 146 cred = p->p_cred; 147 148 /* 149 * Make sure the process has not set-id, to prevent data leaks, 150 * unless it was specifically requested to allow set-id coredumps. 151 */ 152 if (p->p_flag & PK_SUGID) { 153 if (!security_setidcore_dump) { 154 error = EPERM; 155 mutex_exit(p->p_lock); 156 mutex_exit(proc_lock); 157 goto done; 158 } 159 pattern = security_setidcore_path; 160 } 161 162 /* Lock, as p_limit and pl_corename might change. */ 163 lim = p->p_limit; 164 mutex_enter(&lim->pl_lock); 165 if (pattern == NULL) { 166 pattern = lim->pl_corename; 167 } 168 error = coredump_buildname(p, name, pattern, MAXPATHLEN); 169 mutex_exit(&lim->pl_lock); 170 171 if (error) { 172 mutex_exit(p->p_lock); 173 mutex_exit(proc_lock); 174 goto done; 175 } 176 177 /* 178 * On a simple filename, see if the filesystem allow us to write 179 * core dumps there. 180 */ 181 lastslash = strrchr(name, '/'); 182 if (!lastslash) { 183 vp = p->p_cwdi->cwdi_cdir; 184 if (vp->v_mount == NULL || 185 (vp->v_mount->mnt_flag & MNT_NOCOREDUMP) != 0) 186 error = EPERM; 187 } 188 189 mutex_exit(p->p_lock); 190 mutex_exit(proc_lock); 191 if (error) 192 goto done; 193 194 /* 195 * On a complex filename, see if the filesystem allow us to write 196 * core dumps there. 197 * 198 * XXX: We should have an API that avoids double lookups 199 */ 200 if (lastslash) { 201 char c[2]; 202 203 if (lastslash - name >= MAXPATHLEN - 2) { 204 error = EPERM; 205 goto done; 206 } 207 208 c[0] = lastslash[1]; 209 c[1] = lastslash[2]; 210 lastslash[1] = '.'; 211 lastslash[2] = '\0'; 212 error = namei_simple_kernel(name, NSM_FOLLOW_NOEMULROOT, &vp); 213 if (error) 214 goto done; 215 if (vp->v_mount == NULL || 216 (vp->v_mount->mnt_flag & MNT_NOCOREDUMP) != 0) 217 error = EPERM; 218 vrele(vp); 219 if (error) 220 goto done; 221 lastslash[1] = c[0]; 222 lastslash[2] = c[1]; 223 } 224 225 pb = pathbuf_create(name); 226 if (pb == NULL) { 227 error = ENOMEM; 228 goto done; 229 } 230 NDINIT(&nd, LOOKUP, NOFOLLOW, pb); 231 if ((error = vn_open(&nd, O_CREAT | O_NOFOLLOW | FWRITE, 232 S_IRUSR | S_IWUSR)) != 0) { 233 pathbuf_destroy(pb); 234 goto done; 235 } 236 vp = nd.ni_vp; 237 pathbuf_destroy(pb); 238 239 /* 240 * Don't dump to: 241 * - non-regular files 242 * - files with links 243 * - files we don't own 244 */ 245 if (vp->v_type != VREG || 246 VOP_GETATTR(vp, &vattr, cred) || vattr.va_nlink != 1 || 247 vattr.va_uid != kauth_cred_geteuid(cred)) { 248 error = EACCES; 249 goto out; 250 } 251 vattr_null(&vattr); 252 vattr.va_size = 0; 253 254 if ((p->p_flag & PK_SUGID) && security_setidcore_dump) { 255 vattr.va_uid = security_setidcore_owner; 256 vattr.va_gid = security_setidcore_group; 257 vattr.va_mode = security_setidcore_mode; 258 } 259 260 VOP_SETATTR(vp, &vattr, cred); 261 p->p_acflag |= ACORE; 262 263 io.io_lwp = l; 264 io.io_vp = vp; 265 io.io_cred = cred; 266 io.io_offset = 0; 267 268 /* Now dump the actual core file. */ 269 error = (*p->p_execsw->es_coredump)(l, &io); 270 out: 271 VOP_UNLOCK(vp); 272 error1 = vn_close(vp, FWRITE, cred); 273 if (error == 0) 274 error = error1; 275 done: 276 if (name != NULL) 277 PNBUF_PUT(name); 278 return error; 279 } 280 281 static int 282 coredump_buildname(struct proc *p, char *dst, const char *src, size_t len) 283 { 284 const char *s; 285 char *d, *end; 286 int i; 287 288 KASSERT(mutex_owned(proc_lock)); 289 290 for (s = src, d = dst, end = d + len; *s != '\0'; s++) { 291 if (*s == '%') { 292 switch (*(s + 1)) { 293 case 'n': 294 i = snprintf(d, end - d, "%s", p->p_comm); 295 break; 296 case 'p': 297 i = snprintf(d, end - d, "%d", p->p_pid); 298 break; 299 case 'u': 300 i = snprintf(d, end - d, "%.*s", 301 (int)sizeof p->p_pgrp->pg_session->s_login, 302 p->p_pgrp->pg_session->s_login); 303 break; 304 case 't': 305 i = snprintf(d, end - d, "%lld", 306 (long long)p->p_stats->p_start.tv_sec); 307 break; 308 default: 309 goto copy; 310 } 311 d += i; 312 s++; 313 } else { 314 copy: *d = *s; 315 d++; 316 } 317 if (d >= end) 318 return (ENAMETOOLONG); 319 } 320 *d = '\0'; 321 return 0; 322 } 323 324 static int 325 coredump_write(struct coredump_iostate *io, enum uio_seg segflg, 326 const void *data, size_t len) 327 { 328 int error; 329 330 error = vn_rdwr(UIO_WRITE, io->io_vp, __UNCONST(data), len, 331 io->io_offset, segflg, 332 IO_NODELOCKED|IO_UNIT, io->io_cred, NULL, 333 segflg == UIO_USERSPACE ? io->io_lwp : NULL); 334 if (error) { 335 printf("pid %d (%s): %s write of %zu@%p at %lld failed: %d\n", 336 io->io_lwp->l_proc->p_pid, io->io_lwp->l_proc->p_comm, 337 segflg == UIO_USERSPACE ? "user" : "system", 338 len, data, (long long) io->io_offset, error); 339 return (error); 340 } 341 342 io->io_offset += len; 343 return (0); 344 } 345 346 static off_t 347 coredump_offset(struct coredump_iostate *io) 348 { 349 return io->io_offset; 350 } 351
Indexes created Sun Sep 21 18:09:52 GMT 2025